EP0665502B1 - Asynchrone serielle kommunickationsschaltung - Google Patents

Asynchrone serielle kommunickationsschaltung Download PDF

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Publication number
EP0665502B1
EP0665502B1 EP94309902A EP94309902A EP0665502B1 EP 0665502 B1 EP0665502 B1 EP 0665502B1 EP 94309902 A EP94309902 A EP 94309902A EP 94309902 A EP94309902 A EP 94309902A EP 0665502 B1 EP0665502 B1 EP 0665502B1
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EP
European Patent Office
Prior art keywords
data
serial
transmitter
transmit
receiver
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English (en)
French (fr)
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EP0665502A1 (de
Inventor
David A. Banman
Robert A. Clark
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Sun Microsystems Inc
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Sun Microsystems Inc
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F5/00—Methods or arrangements for data conversion without changing the order or content of the data handled
    • G06F5/06—Methods or arrangements for data conversion without changing the order or content of the data handled for changing the speed of data flow, i.e. speed regularising or timing, e.g. delay lines, FIFO buffers; over- or underrun control therefor
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
    • G06F13/38—Information transfer, e.g. on bus
    • G06F13/382—Information transfer, e.g. on bus using universal interface adapter
    • G06F13/385—Information transfer, e.g. on bus using universal interface adapter for adaptation of a particular data processing system to different peripheral devices

Definitions

  • This invention relates, in general, to the field of microprocessor serial communications and, more particularly, to an improved interface between an asynchronous serial port and an IEEE 1496 SBus, including support for infrared data transmission and reception.
  • UART's Universal Asynchronous Receiver Transmitter
  • UART's Universal Asynchronous Receiver Transmitter
  • UART's Universal Asynchronous Receiver Transmitter
  • this solution suffers from two additional deficiencies. First, since the internal buffer included in these buffered UART's is so small, it is still necessary to occasionally turn off the flow of data completely so as to avoid a data overrun. Second, since the buffering is done within the UART itself, control over the buffering process is removed from the system's CPU, thereby decreasing overall flexibility in the processing of incoming data.
  • EP 0359137 National Semiconductor Corporation
  • the improved asynchronous serial communications circuit of the invention provides an interface between multiple serial ports and the SBus as defined by IEEE Std 1496-1993.
  • the circuit is optimized for high data transfer rates while maintaining a low interrupt level and low interrupt frequency.
  • the communications circuit incorporates large FIFO buffers, separate and apart from those incorporated within the actual communications UART's, to buffer both incoming and outgoing data.
  • the SBus interrupt is programmable, thereby allowing the interrupt frequency to be adjusted based on current data transfer rates, the overall system environment and actual system loading.
  • a control mechanism preferably in the form of a state machine, is then implemented to control the interrupts to the main CPU in connection with capacity of each of the FIFO buffers, and to what extent each FIFO buffer may be filled, at any point in time, as a percentage of its maximum capacity.
  • the improved circuit can perform the address decode and transfer acknowledge required for an FCode PROM or NVRAM.
  • the improved circuit can provide the required decode and ACK signals for an additional read/write 8-bit device.
  • the communications circuit incorporates a multi-mode infra-red transmission and reception system which can handle modulation, demodulation and input multiplexing in order to be able to transmit and receive data in formats compatible with those currently in use, including those of multiple frequency modulation standards as well as current pulse modulation standards.
  • Figure 1 is a block diagram of computer system which incorporates the asynchronous serial control circuit of the instant invention.
  • FIG. 2 is a block diagram of the serial control and data paths of the instant invention.
  • FIG. 3 is a block diagram of the infra-red control circuitry of the instant invention.
  • Figure 4 is a state diagram illustrating SBus transfers in accordance with the instant invention.
  • Figure 5 is a state diagram illustrating internal data transfers in accordance with the instant invention.
  • Figure 6 is a timing diagram illustrating a sample frequency modulated infra-red waveform.
  • Figure 7 is a timing diagram illustrating a sample pulse modulated infra-red waveform.
  • the manipulations performed are often referred to in terms, such as adding or comparing, that are commonly associated with mental operations performed by a human operator. No such capability of a human operator is necessary, or desirable in most cases, in any of the operations described herein that form part of the present invention; the operations are machine operations.
  • Useful machines for performing the operations of the present invention include general purpose digital computers or other similar devices. In all cases there should be borne in mind the distinction between the method of operations in operating a computer and the method of computation itself.
  • the present invention relates to method steps for operating a computer in processing electrical or other (e.g. mechanical, chemical) physical signals to generate other desired physical signals.
  • the present invention also relates to an apparatus for performing these operations.
  • This apparatus may be specially constructed for the required purposes, or it may comprise a general purpose computer as selectively activated or reconfigured by a computer program stored in the computer.
  • the algorithms presented herein are not inherently related to any particular computer or other apparatus.
  • various general purpose machines may be used with programs written in accordance with the teachings herein, or it may prove more convenient to construct a more specialized apparatus to perform the required method steps. The required structure for a variety of these machines will appear from the description given below.
  • the asynchronous serial control circuit and infra-red interface of the instant invention is designed to be implemented on a new IEEE 1496-1993 standard SBus based workstation developed by Sun Microsystems, Inc. of Mountain View, California.
  • the invention provides for improved serial communications through the use of FIFO buffered UART's, resulting in lower central processor overhead when processing incoming and outgoing serial data.
  • the invention also provides for a flexible infra-red (IR) interface which allows for communications between, and the control of, personal information managers (PIM's), as well as other devices which may be controlled using an IR remote control.
  • PIM's personal information managers
  • FIG. 1 a block diagram of a computer system which incorporates the asynchronous control circuit of the instant invention, including multi-interface IR support, is shown.
  • a MicroSPARC II processor 12, which functions as a central processing unit (CPU).
  • CPU 12 communicates with the rest of the system across an expandable memory bus, 13, which is preferably 64 bits in width, such as the IEEE standard 1496-1993 SBus, 30, developed by Sun Microsystems, Inc. of Mountain View, California.
  • the main control functions all communicate with CPU 12 across the SBus 30. These functions include the processing of general system input/output through the SLAVIO function, 14, which provides support for a system keyboard, mouse, floppy disk drive and other basic system functions including a time of day clock and power management.
  • the system further includes a MACIO function, 16, which provides support for parallel devices, SCSI devices and TPE devices.
  • a DBRI function, 18, is provided which supports audio input/output and also provides for an integrated ISDN telephone/data connection.
  • Video support is provided through a VIDEO function, 20, which is designed to support both an external monitor as well as an alternative display device, such as a liquid crystal display panel.
  • the CPU 12 is further connected to a PCMCIA support circuit, 22, which may support multiple PCMCIA sockets.
  • PCMCIA support circuit 22
  • the improved architecture of the instant invention provides for a direct connection across the SBus 30, from the CPU 12, to an improved asynchronous serial control circuit (MIC) 24, which, as noted above, also incorporates an IR transceiver 25.
  • MIC asynchronous serial control circuit
  • FIG. 2 a block diagram further detailing MIC 24 is shown.
  • the systems includes two serial ports in addition to an IR port.
  • only one serial port and the IR port is shown.
  • the second serial would contain the identical connections.
  • MIC 24 supports a 16 bit SBus slave interface.
  • the interface supports the following connections to the SBus, including signals transferred over SBus Data line 52 and SBus Control and Status Signal line 54: data [15:0] [bidirectional] addr [3:0] [input] func [2:0] [input] siz [2:0] [input] as_ [input] ack_ [2:0] [output] sb_rst_ [input] sb_clk [input] Sel_ [input] intreq_ [output] rd [input] and further supports memory expansion connections over expansion signal line 55, including mem_rd_ [output] mem_wr_ [output] expan_cs_ [output]
  • the SBus master When the initiated transfer size is greater than the acknowledge size, the SBus master is forced to perform dynamic bus sizing. When a Byte transfer is initiated on the Status or Control Lines 54 the Sbus master is forced to transfer the data on the byte port 52. Burst or Extended transfers will be responded to with an Error Acknowledgement. A write request to transmit FIFO 56, when it is full, will also receive an Error Acknowledgement.
  • the invention also provides support for connecting 8 bit devices to the SBus. This is accomplished through the use of three signals transmitted along the Expansion Signals line, 55. These three signals are mem_rd_, mem_wr_, and expan_cs.
  • the invention drives the mem_rd line low.
  • the circuit After 6 clocks, the circuit provides a byte transfer acknowledge to the SBus. This long acknowledgement time allow for the use of PROM's with worst case access times of 280ns or less on a 25Mhz SBus.
  • mem_rd_ is driven high.
  • An SBus write to PROM/NVRAM address space then causes the mem_we_ signal to be asserted, and a byte acknowledgement to be returned.
  • the mem_rd_ line may be connected to the output enable of a PROM or in the case of an NVRAM, the mem_rd_ and mem_wr_ signals may be used together to perform SBus reads and writes.
  • the invention drives the expan_cs_ line low.
  • the expansion device may use the SBus rd line to determine the transfer direction. Then, after 6 clocks, the circuit provides a byte transfer acknowledge to the SBus.
  • the IR logic 80 interface portion of MIC 24 is shown. This circuitry is also shown in greater detail in Figure 3. As described above, the control circuit provides an IR interface for the support of both frequency modulation and pulse modulation transmission and reception protocols.
  • the complete IR system comprises two parts: the digital logic portion and the analog modulation/demodulation portion. Preferably all of the digital logic may incorporated directly into MIC 24, while the analog components may be external, in order to increase system flexibility and permit the incorporation of new modulation standards in the future.
  • the IR logic is controlled by two registers, IR_MODE and IR_DIVISOR. IR_MODE controls the type of modulation/encoding for transmission and reception (FM or PM), while the IR_DIVISOR controls the frequency of modulation when IR_MODE is in FM mode.
  • an asynchronous serial bit stream is "OR'ed" with a single frequency modulation in order to arrive at an output signal.
  • An example of such modulation is illustrated in Figure 6.
  • the FM signal may typically have a range of between 20kHz to 500kHz, with 500kHz being typical for current PIM communications, while 20kHz to 100kHz is typical for consumer remote controls.
  • this type of modulation is simple to perform.
  • the IR signal is turned off during the "1" bit times and during the 'spacing' period of the serial signal to be encoded. During the "0" bit times, which includes the start bit, the IR signal is turned on and off at the modulation frequency.
  • the modulation circuitry needed to implement such a scheme is simply an OR gate coupling the modulation frequency signal with the serial data signal.
  • the IR signal is turned on for 3/16th of the bit period during any "0" bit, which includes the start bit.
  • the modulation circuitry within the circuit to implement this functionality consists of a state machine which is preferably clocked at 16 times the bit rate.
  • the input to the state machine is the normal asynchronous serial output from the UART 76.
  • the state machine looks for a "0" bit, puts out an active signal for 3/16 bit time, and returns the output to the inactive state for the remainder of the bit period.
  • the decoding process is performed by the analog receiving circuitry, so the signal being input into the MIC circuit 24 will appear as a standard, asynchronous serial signal.
  • the decoding circuit includes a state machine which employs an input latch to catch an active going "0" signal, and generates an output pulse which lasts for a full bit time. Halfway through the output pulse, the latch is reset to catch any pulses which may deviate from the nominal bit rate. If no active going edge has been caught before the end of the bit time, the state machine assumes that the bit is now a "1" bit, and resets itself to continue looking for the "0" edge.
  • the UART Since the output of the decoder is the input for UART 76, the UART will be looking for a starting edge, then interpolating to the center of the nominal bit period, and sample the input signal at the nominal bit center. This will obviate any small glitches if, for example, a sequential series of "0" bits are received, and the actual bit time is slightly longer than in the receiving circuit if, for example, there is a clock mismatch between the sending device and the receiving circuit. In this case there will be brief, erroneous "1" states at the beginning of each nominal "0" bit time, after the first one. Due to the center point sampling of the UART, these glitches will not be detected unless the clock mismatch exceeds the level normally tolerated by asynchronous devices.
  • FIG. 3 A block diagram of a circuit which may perform the above noted IR processes is provided in Figure 3. As illustrated, the IR block may be broken down into two subsystems, a digital processing portion internal to the circuit of the invention 90 and an analog portion which may be external 100. Looking first at the internal digital circuitry, data is brought into and out of the system through an SCC (UART) 76. This circuit has a TX output which is either brought straight, for standard serial communications, or is brought into a modulation gate 91 or HP encoder state machine 92. As discussed above, in the case of transmission of data as illustrated in Figure 6, the modulation frequency to be mixed against the serial data to be transmitted is combined in modulation gate 91. This modulation signal may be generated in any suitable manner.
  • SCC UART
  • this signal is provided in the chain illustrated through elements 93, 94 and 95, which provides a suitable modulation signal derived from an 19.66 MHz clock.
  • the serial signal to be transmitted is used to drive an HP encoder state machine 92.
  • the output of gate 91 or state machine 92 is then used to drive a multiplexer 96 which, in turn, drives an IR element and associated support circuitry 101.
  • an IR signal is received by a detector 102.
  • the output of this detector is conditioned through an amplifier 103 and then demodulated by demodulator 104.
  • the output of demodulator 104 is routed in a number of ways depending on the type of data received.
  • the data may be from a consumer IR signal (rx_lo_mod); a high frequency signal, such as one supplied from an Apple Newton PIM (rx_hi_mod); or a pulse modulated signal such as one supplied from a Hewlett-Packard PIM (rx_p_mod).
  • Pulse Modulated signal such as one supplied from an HP 95LX, as illustrated in Figure 7 and described above
  • SCC (UART) 76 it must first be 'stretched' into a duty cycle which is compatible. This is done in a pulse stretcher state machine 97, the output of which is then provided to a multiplexer 98. Multiplexer 98 then is used to control the input from all the noted serial data signals, including a standard hard wired serial data connection, into SCC (UART) 76.
  • the flow logic control portion of the MIC asynchronous serial communications circuit 24 is examined.
  • An advantage of the instant invention is that, unlike other serial solutions, the instant invention supports automatic serial hardware flow control, including RTS and CTS. In order for this feature to be activated, the RTS Automatic Control Register and the CTS Automatic Control Register must both be enabled.
  • Rts_ is a status output signal which controls the transmitter of the connected serial device.
  • the rts_ line is controlled manually by the RTS_STAT register.
  • the RTS_AUTO_EN register is set high, rts_ is automatically controlled by the inventions control logic.
  • auto rts control if the receive FIFO count becomes greater than or equal to 61, rts_ is disabled (driven high).
  • the connected serial device may transmit 3 additional data bytes before overflowing the receiving UART. Rts_ will then stay disabled until the receive FIFO count is less than 61.
  • Cts_ is a control input which can be set to directly control the transmission of data from the invention's serial port.
  • the invention's transmitter When the CTS_AUTO_EN register is reset low, the invention's transmitter is always enabled, and the cts_ line is ignored. However, if the CTS_AUTO_EN register is set high, cts_ will control the transfer of data from the transmit FIFO to the respective UART. If the cts_ line is disabled, the invention's control logic will stop transferring data to the respective UART. There can be up to 2 bytes of data already in the UART, which will continue to be shifted out of the transmit port. Once the remaining data in the UART has been transmitted, data transmission will cease until the cts_ line again goes active.
  • the MIC circuit 24 further incorporates a built in time out feature to reduce the interrupt frequency. To be effective it must be used with a receive water mark detector having a detector level of greater than one.
  • the Timer Set Count Register is used to load the respective Receive Timer.
  • the Receive Timer is loaded when a byte is pushed into the respective RX FIFO. It is decremented with each SBus clock until it reaches zero or is set with a new received data byte. If the Receive Tuner reaches zero before the receive water mark level is reached, then a Receive Timeout Interrupt is set.
  • an SCC (UART) Serial Controller is shown. Although only one SCC device is illustrated, in practice two devices, A and B are provided, one for each port. Because the SCC's (UART's) have an 8 bit data bus, all data transfers between the SBus and the SCC's (UART's) are done on the most significant byte of control circuit's half word data bus.
  • SCC's (UART's) have an 8 bit data bus, all data transfers between the SBus and the SCC's (UART's) are done on the most significant byte of control circuit's half word data bus.
  • 16C450 Megafunction refer to the LSI cfn0451 a Specification.
  • 16C450 register set and general operation reference is made to National Semiconductor's 16C450 (16C550) Specification.
  • the MIC circuit incorporates a master state machine 60, which provides control to the IR Logic 80, the SCC UART 76, Flow Control Logic 78, Transmit Counter 68, Receive Counter 70, Timeout Counter 72, Expansion Signals 55, Transmit FIFO 56, and Receive FIFO 58 (which also receives as an input a signal from Encoder 66, which is used to encode the data status signals from the SCC (UART) into a 3bit code, described as the DAT_STAT bits in the Appendix.) Master state machine 60 also communicates with data from the SBus 52, and with CSR (Control and Status Registers) 62.
  • Write Decode block 64 is used during an SBus write to determine, or decode which CSR to write based upon the addresses received.
  • Figure 4 illustrates a state diagram for transfers from the invention on to and off of the SBus. Shown are the execution states for a PROM transfer, a CSR Read, an SCC (UART) Read, a Control Register Write, an SCC (UART) Write, and the state for an illegal (error) transfer.
  • Figure 5 illustrates a state diagram for data transfers within the invention. Shown here are the states for the FIFO A Loop Back Mode, the FIFO B Loop Back Mode, and an SCC (UART) Transfer which further includes those states where the data in SCC (UART) A is ready, the data in SCC (UART) B is ready, SCC A (UART) is empty and SCC (UART) B is empty.
  • FIGS 4 and 5 illustrate the states of the Master State Machine (MSM) 60. As illustrated, with the exception of the IDLE state, MSM 60 never remains in one state for more than one sb_clk. Only one transfer can occur at one time (SBus or Internal).
  • MSM Master State Machine
  • SBus will only initiate one type of SBus transfer at a time. Therefore all SBus transfer types have the same priority.
  • Figure 4 shows all the states associated with SBus Transfers. From the IDLE state, there are 6 transfer paths that can be taken. Movement from the IDLE state is initiated when the SBus sel_ and as_ inputs are asserted. The path taken is controlled by the SBus addr[3:0], func[2:0], and rd inputs. The following is a description of each path.
  • the MSM moves through the PROM transfer path, to PROM_WAIT1, PROM_WAIT2, PROM_WAIT3 PROM_WAIT4, PROM_WAIT5, PROM_ACK6, then PROM_ACK7.
  • PROM_WAIT1 the mem_rd_, mem_wr_, and expans_cs_ output pins are driven as described above.
  • PROM_ACK6 the SBus ack_[2:0] outputs are driven with the Byte Ack code.
  • the mem_wr_and expans_cs_ are driven inactive.
  • PROM_ACK7 the SBus ack_[2:0] outputs are driven inactive.
  • the MSM goes to PRE_IDLE_WAIT. This state is used to give the SBus one cycle to de-assert the as_ and sel_ signals before going to the IDLE state.
  • the MSM goes to the REG_RD state.
  • the Data Output Mux drives the control or status register selected by the addr[3:0] and func[2:0] inputs onto the data[15:0] outputs.
  • the SBus ack_[2:0] outputs are driven with the Half-Word Ack code. In the following state the SBus ack_[2:0] outputs are driven inactive. If the RX FIFO data address is selected, then the RX FIFO is popped and the MSM goes to the FIFO_RD_WAIT state. Otherwise, the MSM goes to the PRE_IDLE_WAIT state.
  • the FIFO_RD_WAIT state is to allow the RX FIFO status signals enough time to stabilize before another SBus read is issued.
  • the MSM goes to the SCC_RD state. During this state the SCC data bus is driven onto the SBus data [15:8] output pins. Additionally, the SBus ack_[2:0] outputs are driven with the Byte Ack code. In the following state, PRE_IDLE_WAIT, the SBus ack [2:0] outputs are driven inactive.
  • the MSM When the Control Register address space is written, the MSM goes to the REG_WRT state. During this state, the Write Decode Logic latches the SBus data inputs in to the selected register. In the following state, if the TX FIFO is selected, the SBus ack_[2:0] outputs are driven with the Byte Ack code. Otherwise, the SBus ack_[2:0] outputs are driven with the Half-Word Ack code. On the following sb_clk, the MSM goes to the INACTIVE_ACK state. In this state, the SBus ack_[2:0] outputs are setup to be driven inactive in the following state.
  • the MSM goes to the SCC WRT state. During this state, the SBus data inputs are multiplexed onto the SCC data bus. In the following state, the data is latched and the Byte Ack code is driven.
  • FIG. 5 shows all the states associated with Internal Data Transfers.
  • Each internal transfer type has two paths, one for each port (A and B). The following is a description of each type. Since the transfers types for the A and B ports are identical, each transfer type will be described only once.
  • the TX FIFOs can be setup to loop back data to the RX FIFOs. If this TXFF_TO_RXFF test mode is set and there is data in the TX FIFO, then the MSM goes to the TXFF_TO_RXFF state. During this state, the RX FIFO is pushed with the data from the TX FIFO. In the following state, the TX FIFO is popped. The MSM goes to the PRE_IDLE_WAIT state so that all the status signals from the FIFOs and SCC's can stabilize before going to the IDLE state.
  • the MSM When the SCC has received data ready, the MSM begins an SCC to RX FIFO transfer. As with all internal SCC data transfers, the address going to the SCC must be switched to 0. This is done in the SCC ADDR SETUP state. Then the MSM goes to the SCC_TO_RXFF state. During this state, the received data is read from the SCC and pushed in to the RX FIFO.
  • the MSM When the SCC transmit buffer is empty and data is available in the TX FIFO, the MSM begins a TX FIFO to SCC transfer. After the SCC address has been set in the SCC_ADDR_SETUP state, the MSM goes to the TXFF_TO_SCC state. During this state, the top TX FIFO data is written in to the SCC. In the following state, the TX FIFO is popped.
  • TX FIFO 56 data to be transmitted from the system out across a serial port (either hard wired or IR) is first buffered by TX FIFO 56. Control of this FIFO is performed by the Master State Machine 60. This data is then routed to the SCC (UART) 76 and processed as described. (Although a direct connection is shown between the SBus data line 52 and a multiplexer 57, in practice this connection is used only the program the SCC (UART) registers, while the TX FIFO 56 is always used only for data.) A similar flow is found on the receive side where information received into SCC (UART) 76 is coupled to RX FIFO 58, which is also under the control of Master State Machine 60.
  • RX FIFO 58 is external to SCC (UART) 76, it is anticipated that modifications to the invention may provide for greater storage in RX FIFO 58 in order to further reduce the need for the CPU to process data and interrupt requests.
  • RX FIFO 58 is also more flexible in that under the control of Master State Machine 60, various schemes may be implemented to optimize system throughput while minimizing interrupt requests.
  • Timeout Counter 72 This can be accomplished in connection with TX Counter 68, RX Counter 70 and Timeout Counter 72. In one embodiment it is recommended that an interrupt be generated only every 30 characters. This may be measured and controlled by RX Counter 70. However, in the case of data received slowly (such as from an external IR keyboard), 30 characters may take many seconds (or more) to be received. In such a case Timeout Counter 72 will then be used in addition to RX Counter 70 to force an interrupt to occur before 30 characters have been received, in order to smooth the user interface.
  • an improved serial control circuit may be provided which includes support for multiple IR protocols.
  • Using the improved serial control circuit results in the need for fewer components, the need for less physical space on a printed circuit board, lower power consumption and lower construction and implementation costs.
  • the functionality of the invention is embodied in a single integrated circuit, it is anticipated that multiple devices may also be used, or that functionality may also be simulated through the use of a universal processing engine and appropriate control instructions.
  • an improvement over devices currently on the market is realized in that a direct connection to an IEEE SBus is provided, obviating the need for hardware and software to 'translate' signals and data between a generic bus and the SBus.

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Claims (11)

  1. Eine serielle Kommunikationsschaltung (24), die mit einem Datenverarbeitungssystem (12) und einem seriellen Port gekoppelt ist, aufweisend:
    a) einen mit dem seriellen Port gekoppelten ersten seriellen Empfänger und Sender (76) zum Empfangen und Senden serieller Daten;
    b) einen mit dem ersten seriellen Empfänger und Sender (76) gekoppelten und außerhalb von diesem befindlichen Sendepuffer (56) zum temporären Speichern von Sendedaten aus dem Datenverarbeitungssystem (12) und zum Bereitstellen der Sendedaten an den ersten seriellen Empfänger und Sender (76);
    c) einen mit dem ersten seriellen Empfänger und Sender (76) gekoppelten und außerhalb von diesem befindlichen Empfangspuffer (58) zum temporären Speichern empfangener Daten aus dem seriellen Port und zum Bereitstellen der Daten an das Datenverarbeitungssystem (12);
    d) ein dem Sendepuffer zugeordnetes Senderegister zum Speichern eines ersten vorgegebenen Werts, wobei der erste vorgegebene Werf die maximale Kapazität des Sendepuffers (56) anzeigt;
    e) ein dem Empfangspuffer zugeordnetes Empfangsregister zum Speichern eines zweiten vorgegebenen Werts, wobei der zweite vorgegebene Wert die maximale Kapazität des Empfangspuffers (58) anzeigt;
    f) einen Sendezähler (68) zum Halten einer Sendepufferzählung, wobei die Sendepufferzählung die aktuelle Menge der Daten in dem Sendepuffer (56) anzeigt;
    g) einen Empfangszähler (70) zum Halten einer Empfangspufferzählung, wobei die Empfangspufferzählung eine aktuelle Menge von Daten in dem Empfangspuffer (58) anzeigt; und
    h) eine mit dem ersten seriellen Empfänger und Sender (76), dem Sendepuffer (56), dem Empfangspuffer (58), dem Senderegister, dem Empfangsregister, dem Sendezähler und dem Empfangszähler gekoppelte Datenflußsteuereinrichtung (60), die es den Daten ermöglicht, in den Sende- bzw. den Empfangspuffer zu fließen, wenn die Sendepufferzählung geringer als der erste vorgegebene Wert bzw. die Empfangspufferzählung geringer als der zweite vorgegebene Wert ist, und zum Stoppen des Datenflusses in den Sende- bzw. Empfangspuffer und zum Übertragen der Sendedaten und Empfangsdaten an den seriellen Port bzw. das Datenverarbeitungssystem, wenn die Sendepufferzählung bzw. die Empfangspufferzählung gleich dem ersten vorgegebenen Wert bzw. dem zweiten vorgegebenen Wert ist oder diesen überschreitet,
       wobei die Datensteuereinrichtung das Datenverarbeitungssystem auf der Grundlage der Sendepufferzählung und der Empfangspufferzählung unterbricht; und
       wobei das Senderegister und das Empfangsregister von dem Datenverarbeitungssystem derart programmierbar sind, daß das Datenverarbeitungssystem die Häufigkeit steuern kann, bei welcher das Datenverarbeitungssystem von der Datensteuereinrichtung unterbrochen wird, indem sie den ersten und den zweiten vorgegebenen Wert ändert, so daß die Unterbrechungsfrequenz auf einer aktuellen Datenübertragungsrate zwischen dem Datenverarbeitungssystem und dem seriellen Port und einer aktuellen Belastung des Datenverarbeitungssystem basiert.
  2. Die serielle Steuerkommunikationsschaltung, wie sie in Anspruch 1 beansprucht ist, wobei der erste serielle Empfänger/Sender ferner einen Infrarot-Empfänger /Sender (80) zum Empfangen eines Infrarotsignals und zum Konvertieren des Signals in ein Signal, welches von dem ersten seriellen Empfänger/Sender verarbeitet werden kann, und zum Empfangen eines Signals aus dem ersten seriellen Empfänger/Sender und zum Konvertieren des Signals in ein Signal, welches als Infrarotenergiestrahl gesendet werden kann, aufweist.
  3. Die serielle Steuerkommunikationsschaltung, wie sie in Anspruch 2 beansprucht ist, wobei das Infrarctsignal ein digitales Datensignal aufweist, welches frequenzmoduliert worden ist.
  4. Die serielle Steuerkommunikationsschaltung, wie sie in Anspruch 3 beansprucht ist, ferner aufweisend einen zwischen dem Senderabschnitt des Infrarot-Empfängers/Sender und dem ersten seriellen Empfänger/Sender eingekoppelten Frequenzmodulationsmechanismus zum Konvertieren eines digitalen Signals in ein frequenzmoduliertes Signal vor der Mcdulation durch den Infrarotsender.
  5. Die serielle Steuerkommunikationsschaltung, wie sie in Anspruch 4 beansprucht ist, wobei der Frequenzmodulationsmechanismus das digitale Signal in Übereinstimmung mit einem anerkannten Industriestandard moduliert.
  6. Die serielle Steuerkommunikationsschaltung, wie sie in Anspruch 2 beansprucht ist, wobei das Infrarotsignal ein digitales Datensignal aufweist, welches impulsmoduliert worden ist.
  7. Die serielle Steuerkommunikationsschaltung, wie sie in Anspruch 6 beansprucht ist, ferner aufweisend einen Impulsdehnungsmechanismus (97), der zwischen dem Empfängerabschnitt des Infrarot-Empfängers/Senders und dem ersten seriellen Empfänger/Sender eingekoppelt ist, zum Konvertieren des impulsmodulierten Signals in ein digitales Signal.
  8. Die serielle Steuerkommunikationsschaltung, wie sie in Anspruch 6 beansprucht ist, ferner aufweisend einen Impulscodiermechanismus, der zwischen dem Senderabschnitt des Infrarot-Empfängers/Senders und dem ersten seriellen Empfänger/Sender eingekoppelt ist, zum Konvertieren eines digitalan Signals in ein impulsmoduliertes Signal vor der Modulation durch den Infrarotsender.
  9. Die serielle Steuerkommunikationsschaltung, wie sie in Anspruch 1 beansprucht ist, wobei das Datenverarbeitungssystem einen Datenbus enthält, welcher den Spezifikationen des IEEE-Standards 1496-1993 genügt.
  10. Die serielle Steuerkommunikationsschaltung, wie sie in Anspruch 1 beansprucht ist, ferner enthaltend einen zweiten seriellen Empfänger/Sender zum Empfangen und Senden serieller Daten außerhalb der Kommunikationsschaltung über einen zweiten seriellen Port.
  11. Die serielle Steuerkommunikationsschaltung, wie sie in Anspruch 1 beansprucht ist, wobei die Datenflußsteuereinrichtung es ferner Daten ermöglicht, in den Sendepuffer eingegeben oder aus dem Sendepuffer entfernt zu werden, nachdem eine erste vorgegebene Zeitdauer abgelaufen ist, unabhängig davon, ob der Sendepuffer bis zum einem zuvor definierten Prozentsatz seiner maximalen Kapazität gefüllt worden ist.
EP94309902A 1994-01-27 1994-12-29 Asynchrone serielle kommunickationsschaltung Expired - Lifetime EP0665502B1 (de)

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